The aim of the study. Conduct a digital analysis of the distribution of relative force occlusal load in the area of the second permanent mandibular molars before and after their mesialization. Research methods. In order to evaluate the distribution of inter-occlusal force load in the process of mesialization of molars on the mandible, two clinical study groups were formed. The first group consisted of 32 persons (18 women / 56.25% and 14 men / 43.75%) aged from 18 to 25 years, who had orthodontic treatment using braces and mini-implants. The second group included 30 people (19 women / 63.33% and 11 men / 36.67%), orthodontic treatment was performed using a brace system without additional intraosseous support on the mini-implants. T-scan apparatus investigated the distribution of relative force occlusal load in the area of the second permanent mandibular molars before and after orthodontic intervention. Results of the study. The use of the T-scan apparatus is an accurate and informative tool for analyzing the distribution of functional occlusal force load within the dentition. During the analysis of the parameters of the chewing load in the area of the second permanent molars on the mandible before orthodontic treatment, an increase of this index was found in almost all patients of both study groups. In the first group in 4 (12.5%) persons the maximum relative occlusive force load in the area of the second permanent molars on the mandible was 10–20%, which is the range of the norm; in 15 (46.9%) cases this indicator was 20–30. %, in 10 (31.2%) patients had 30-40%, and in 3 (9.4%) exceeded 40%. In the second group, the parameters of the relative force occlusal load in the area of the second permanent molar on the mandible were as follows: in 5 (16.7%) persons in the range of 10-20%, in 13 (43.3%) persons - 20-30%, in 10 (33.3%) patients - 30-40% and in 2 (6.7%) patients more than 40%. After treatment, normalization of the relative occlusal force load was observed in the area of the second permanent molars on the lower jaw in the majority of patients of both study groups. In particular, in the first group in 21 (65.6%) persons the parameters of occlusal load were in the range of 10–20%, in 11 (34.4%) persons were 20–30%. In the second study group, 17 (56.7) patients observed parameters of the occlusal load on the second molar in the range of 10-20%, in 12 (40%) persons - 20-30% and in one (3.3%) patient 30-40%. In addition, moving molars involves changing the usual occlusal ratios associated with the non-identity factor in the shape and size of the first and second molars. At the same time, occlusal contacts on all other teeth are altered due to their alignment with the orthodontic equipment and the appearance of new contact points that did not interact before the start of treatment. Conclusions. The analysis of the distribution of the relative occlusal load in the area of the second permanent molars on the lower jaw with the help of T-scan after orthodontic treatment revealed the normalization of this indicator in the majority of patients in both study groups. Specifically, in the first group, 21 (65.6%) subjects had parameters of relative occlusal load within the range of 10–20%, and in 11 (34.4%) individuals were 20–30%. In the second study group, 17 (56.7%) patients were in the range of 10–20%, 12 (40%) patients - 20–30% and one (3.3%) patients 30–40%. The data obtained in both the first and second study groups indicate the need to perform procedures of grinding after orthodontic intervention to achieve appropriate occlusive normalization, the volume of which in each clinical situation is determined individually under the control of the T-scan apparatus.
The aim: To substantiate the need for a combination of interdisciplinary approaches to diagnosis, treatment and correction of dento-maxillofacial anomalies of teenagers based on the analysis of the need for orthodontic treatment using the DAI, IOTN, ICON aesthetic indices. Materials and methods: Empirical, epidemiological, clinical, analytical-synthetic, sociological, psychological research methods, questionnaires, dental indexeshave been used in various combinations. Results: As a result of a clinical examination of 2,260 teenagers (1,096 boys and 1,124 girls), 1,474 individuals have been bselected for orthodontic treatment with the following degree of complexity: mild – in 25 examined (35.71±4.95%), moderate – in 31 individuals (44.28± 5.48%), heavy – 14 (20.00±3.11%). After an in-depth dental examination and determination of the psychological profile, 70 teenagers have been selected for treatment. Conclusions: The effectiveness of the use of dental indices as a screening tool to eliminate the discrepancy between objective medical indicators of the level of need for correction of dento-maxillofacial anomalies and the level of expected results in adolescents has been proven.
The aim of the study. Carry out a comparative analysis of the support ability of human jaw bone tissue in monocortical and bicortical installation of a mini-implant of own design OMG. Research methods. In order to study biomechanical characteristics of developed OMG mini-implant and bone tissue capacity during monocortical and bicortical installation, the finite element method (MSE) was used. The scheme and finite element 2-D model of bicortical installation of OMG mini-implant (length 8 mm, diameter 1.8 mm) provided full penetration through one layer of cortical bone equal to 1 mm, the entire cancellous bone and immersion in the second layer of cortical bone by 0, 5 mm. No implantation was immersed in the second cortical layer of bone during monocortical installation. A single force load of 1 N was applied in the horizontal direction parallel to the cortical plate of the bone. Results of the study. One of the most important factors leading to the success of the use of a mini-implant is its stability in the process of orthodontic treatment. Quite a high level of failure in the monocortical installation of mini-screws has led to the search for better methods to ensure the stability of their use. This was a bicortical method of fixation, based on the placement of the minig screw in the thickness of the two cortical plates of the jaws. Area for such installation of mini-screws can be a site of a palate and alveolar sprouts at installation of miniimplants through all its thickness. As shown by our data on the use of the finite element method under the force load of the biomechanical system "bone - mini-implant", the stress concentration zone is located in the area of the cortical bone of the jaw. The results of the calculation of the maximum stresses (σmax, MPa) and the maximum possible displacements (umax, mm) of the mini-implant in the biomechanical system "bone - mini-implant" in monocortical installation were, respectively, 8.27 MPa and 0.300 * 10-8 mm and in bicortical installation 6.00 MPa and 0.201 * 10-8 mm. The bicortical method of fixing the mini-implant in the jaw bones significantly increases the ability to resist deformation of this type of biomechanical system under force loads of the mini-implant. In the bicortical method of mini-implant placement, the extreme values of equivalent according to Mises stresses in the upper part of the cortical bone of the jaw are reduced by 27%. This can be explained by a significant increase in the area of contact due to the two layers of the cortical bone of the jaw with the surface of the mini-implant. Conclusion. The bicortical method of installing mini-implants is a more effective and reliable way to provide skeletal support during orthodontic treatment.
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